381 lines
11 KiB
C
381 lines
11 KiB
C
/****************************************************************************
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* libs/libc/misc/lib_slcddecode.c
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* Decoding side of the SLCD CODEC
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*
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* Copyright (C) 2013 Gregory Nutt. All rights reserved.
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* Authors: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdint.h>
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#include <stdbool.h>
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#include <assert.h>
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#include <debug.h>
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#include <nuttx/streams.h>
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#include <nuttx/ascii.h>
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#include <nuttx/lcd/slcd_codec.h>
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/* Indices, counts, helper macros ******************************************/
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#define NDX_ESC 0
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#define NDX_BRACKET 1
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#define NDX_CODE3 2
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#define NDX_COUNTH 2
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#define NDX_COUNTL 3
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#define NDX_CODE5 4
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#define NCH_ESC 1
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#define NCH_BRACKET 2
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#define NCH_CODE3 3
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#define NCH_COUNTH 3
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#define NCH_COUNTL 4
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#define NCH_CODE5 5
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#define IS_HEX(a) ((((a) >= '0') && ((a) <= '9')) || \
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(((a) >= 'a') && ((a) <= 'f')))
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#define CODE_MIN ('A' + FIRST_SLCDCODE)
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#define CODE_MAX ('A' + LAST_SLCDCODE)
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#define IS_CODE(a) (((a) >= CODE_MIN) && ((a) <= CODE_MAX))
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#define CODE_RETURN(a) (enum slcdcode_e)((a) - 'A')
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: slcd_nibble
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*
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* Description:
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* Convert a ASCII hexadecimal character (using only lower case alphabetics
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* into a binary nibble
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*
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* Input Parameters:
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* ascii - The nibble characgter.
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*
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* Returned Value:
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* The binary value of the nibble.
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*
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****************************************************************************/
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static uint8_t slcd_nibble(uint8_t ascii)
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{
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if (ascii >= '0' && ascii <= '9')
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{
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return ascii - '0';
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}
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else
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{
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return ascii - 'a';
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}
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}
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/****************************************************************************
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* Name: slcd_reget
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*
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* Description:
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* We have unused characters from the last, unsuccessful decode attempt.
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* Return one of these instead of the new character from the stream.
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*
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* Input Parameters:
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* stream - An instance of lib_instream_s to do the low-level get
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* operation.
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* pch - The location character to save the returned value. This may be
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* either a normal, character code or a special command from enum
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* slcd_keycode_e
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*
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* Returned Value:
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* Always SLCDRET_CHAR
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*
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****************************************************************************/
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static enum slcdret_e slcd_reget(FAR struct slcdstate_s *state,
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FAR uint8_t *pch, FAR uint8_t *parg)
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{
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/* Return the next character */
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*pch = state->buf[state->ndx];
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*parg = 0;
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/* Bump up the indices and return false (meaning a normal character) */
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state->ndx++;
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state->nch--;
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return SLCDRET_CHAR;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: slcd_decode
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*
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* Description:
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* Get one byte of data or special command from the application provided
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* input buffer.
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*
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* Input Parameters:
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* stream - An instance of lib_instream_s to do the low-level get
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* operation.
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* state - A user provided buffer to support parsing. This structure
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* should be cleared the first time that slcd_decode is called.
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* pch - The location to save the returned value. This may be
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* either a normal, character code or a special command from enum
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* slcdcode_e, depending on the return value from slcd_decode()
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* parg - The location to save the count argument that accompanies some
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* special actions
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*
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* Returned Value:
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*
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* false: Normal character
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* true: Special SLCD action code with possible argument
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*
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****************************************************************************/
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enum slcdret_e slcd_decode(FAR struct lib_instream_s *stream,
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FAR struct slcdstate_s *state, FAR uint8_t *pch,
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FAR uint8_t *parg)
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{
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enum slcdcode_e code;
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uint8_t count;
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int ch;
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DEBUGASSERT(stream && state && pch && parg);
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/* Are their ungotten characters from the last, failed parse? */
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if (state->nch > 0)
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{
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/* Yes, return the next ungotten character */
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return slcd_reget(state, pch, parg);
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}
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state->ndx = 0;
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/* No, ungotten characters. Get the next character from the buffer. */
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ch = stream->get(stream);
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if (ch == EOF)
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{
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/* End of file/stream (or perhaps an I/O error) */
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return SLCDRET_EOF;
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}
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/* Save the character (whatever it is) in case we fail parsing later */
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state->buf[NDX_ESC] = (uint8_t)ch;
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state->nch = NCH_ESC;
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/* Check for the beginning of an escape sequence */
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if (ch != ASCII_ESC)
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{
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/* Not the beginning of an escape sequence. Return the character. */
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return slcd_reget(state, pch, parg);
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}
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/* Get the next character from the buffer */
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ch = stream->get(stream);
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if (ch == EOF)
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{
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/* End of file/stream. Return the escape character now. We will
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* return the EOF indication next time.
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*/
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return slcd_reget(state, pch, parg);
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}
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/* Save the character (whatever it is) in case we fail parsing later */
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state->buf[NDX_BRACKET] = ch;
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state->nch = NCH_BRACKET;
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/* Check for ESC-[ */
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if (ch != '[')
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{
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/* Not the beginning of an escape sequence. Return the ESC now,
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* return the following characters later.
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*/
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lcderr("ERROR: Parsing failed: ESC followed by %02x\n", ch);
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return slcd_reget(state, pch, parg);
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}
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/* Get the next character from the buffer */
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ch = stream->get(stream);
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if (ch == EOF)
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{
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/* End of file/stream. Return the ESC now; return the following
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* characters later.
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*/
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return slcd_reget(state, pch, parg);
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}
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/* If the next character is a hexidecimal value (with lower case
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* alphabetic characters), then we are parsing a 5-byte sequence.
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*/
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if (!IS_HEX(ch))
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{
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/* Decode the value following the bracket */
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code = CODE_RETURN(ch);
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count = 0;
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/* Verify the special CLCD action code */
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if (code < (int)FIRST_SLCDCODE || code > (int)LAST_SLCDCODE)
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{
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lcderr("ERROR: Parsing failed: ESC-L followed by %02x\n", ch);
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/* Not a special command code.. put the character in the reget
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* buffer.
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*/
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state->buf[NDX_CODE3] = (uint8_t)ch;
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state->nch = NCH_CODE3;
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/* Return the ESC now and the next two characters later. */
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return slcd_reget(state, pch, parg);
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}
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}
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else
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{
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/* Save the first character of the two byte hexidecimal number */
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state->buf[NDX_COUNTH] = (uint8_t)ch;
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state->nch = NCH_COUNTH;
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/* Get the next character from the buffer */
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ch = stream->get(stream);
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if (ch == EOF)
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{
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/* End of file/stream. Return the ESC now; return the following
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* characters later.
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*/
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return slcd_reget(state, pch, parg);
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}
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/* We expect the next character to be the second byte of hexidecimal
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* count value.
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*/
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if (!IS_HEX(ch))
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{
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/* Not a 5-byte escape sequence. Return the ESC now; return the
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* following characters later.
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*/
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lcderr("ERROR: Parsing failed: ESC-L-%c followed by %02x\n",
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state->buf[NDX_COUNTH], ch);
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return slcd_reget(state, pch, parg);
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}
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/* Save the second character of the two byte hexidecimal number */
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state->buf[NDX_COUNTL] = (uint8_t)ch;
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state->nch = NCH_COUNTL;
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/* Get the next character from the buffer */
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ch = stream->get(stream);
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if (ch == EOF)
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{
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/* End of file/stream. Return the ESC now; return the following
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* characters later.
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*/
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return slcd_reget(state, pch, parg);
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}
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/* Put the character in the reget buffer because there is on more way
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* that we can fail.
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*/
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state->buf[NDX_CODE5] = (uint8_t)ch;
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state->nch = NCH_CODE5;
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/* Get the code and the count values. All count values must be greater
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* than 0 or something is wrong.
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*/
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code = CODE_RETURN(ch);
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count = slcd_nibble(state->buf[NDX_COUNTH]) << 4 |
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slcd_nibble(state->buf[NDX_COUNTL]);
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/* Verify the special CLCD action code */
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if (code < (int)FIRST_SLCDCODE || code > (int)LAST_SLCDCODE)
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{
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/* Not a special command code. Return the ESC now and the rest
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* of the characters later.
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*/
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lcderr("ERROR: Parsing failed: ESC-L-%c-%c followed by %02x\n",
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state->buf[NDX_COUNTH], state->buf[NDX_COUNTL], ch);
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return slcd_reget(state, pch, parg);
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}
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}
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/* We have successfully parsed the entire escape sequence. Return the
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* CLCD value in pch, return the count in parg, and an indication that this
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* is a special action.
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*/
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*pch = code;
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*parg = count;
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state->nch = 0;
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return SLCDRET_SPEC;
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}
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